1. Field of the Invention
The present invention is related to a method for refining virgin plant oil and/or waste vegetable oil into fuel, an oil obtainable by said method and an apparatus for refining virgin plant oil and/or waste vegetable oil into fuel.
2. Description of the Related Art
In Japan, environmental pollution due to waste vegetable oil such as oil used in cooking tempura has been a problem of society for years now. Disposal of waste vegetable oil from restaurants and from the general household involves processing that most consumers regard burdensome.
In an official announcement, waste vegetable oil discarded by the restaurants and food manufacturing industries amounts to approximately 200,000 tons, while another 200,000 tons come from the general household totalling 400,000 tons a year. However, comparing this to the 1.2-1.4 million tons of vegetable oil produced by manufacturers every year, the amount of waste vegetable oil is actually very large.
In the last two to three years, the recycling of waste vegetable oil into diesel engine fuel has been the focus of attention of research and development. Foremost of this is the xe2x80x9cmethylesteric fuel production methodxe2x80x9d. FIG. 11 shows the general principle of this method. According to this method, waste vegetable oil is mixed with methanol or ethanol and a catalyst (sodium hydroxide), heated, and agitated. As shown in the figure, an esteric exchange reaction occurs, separating into methylester and glycerin.
Further elaborating this, FIG. 10 shows the processes in the methylesteric fuel production. For the waste vegetable oil (101) in the pre-treatment process (112), its impurities (admixtures, moisture, free fatty acids) are removed (102, 103, 104) through a distiller ensuring a good fuel yield. Upon completing the pre-treatment process, the waste vegetable oil is transferred (105) to the esteric exchange reaction equipment, mixed with methanol or ethanol at 30k by volume (to be expressed in xe2x80x9c%xe2x80x9d from hereon) and sodium hydroxide as catalyst at 0.10-0.15% of methanol volume, and agitated. Through the eterification process (113) including the process (107) involving water and kaolin, the raw material is finally separated into the fuel (108) and glycerin waste (109). The glycerin waste is further neutralized and decomposed (110), and handed over to the industrial waste processors.
However, this methylesterification technology has the following problems:
(1) Since the process requires mixing the waste vegetable oil with 30-50% methanol or ethanol, the cost of raw material increases.
(2) The cost of constructing the processing plant is made more expensive by the high combustibility of methanol or ethanol.
(3) There are problems in the safety of the operation.
(4) Fuel yield upon refining is low at 70% or less.
(5) Diesel oil produced from this method emits more formaldehyde, acrolein, benzene and the like when used as fuel due to the addition of methanol or ethanol. These emissions are even more than commercially-available diesel oil from petroleum. It would be, thus, difficult, to consider it a xe2x80x9ccleanxe2x80x9d fuel.
This invention aims to provide a method and equipment for refining and recycling virgin plant oil and/or waste vegetable oils which can be used as diesel engine fuel, which allow to overcome the problems of the methylesterification technology. More particularly, a method was to be provided which allowed for the production of fuel from virgin plant oil and/or waste vegetable oil not making use of esterification.
According to the invention, the problem is solved by a method for refining virgin plant oil and/or waste vegetable oil into fuel, preferably diesel engine fuel, whereby said method comprises the steps of
heating the oil
supplying water and/or ozone
mixing the oil with water and/or ozone and
agitating the mixture of oil and water and/or dissipating the ozone.
In an embodiment of the inventive method, said method is characterized in that said steps form a pre-treatment step.
In a further embodiment, the pre-treatment step further comprises a step of separating the oil from the water.
In another embodiment, the oil is heated to a temperature of about 40xc2x0 C. to about 80xc2x0 C.
According to the invention, the water which is preferably ozonated, is supplied in an amount of about 3 to about 8% by volume of the oil, preferably about 5% by volume of the volume of the oil in the inventive method.
In a preferred embodiment, the ozone is supplied from the bottom of a vessel containing at least the oil and the water, preferably with a concentration of about 4,000 to about 30,000 ppm, most preferably about 7,000 ppm.
In another preferred embodiment, the mixing and/or agitating and/or dissipating is done by a screw-type propeller with sawtooth-edged blades, preferably rotating at about 300 rpm.
According to the invention, the pre-treatment takes about 20 to about 30 minutes.
In another embodiment of the inventive method, said method comprises a further step of supplying ozone to the oil.
In a more preferred embodiment, the oil is heated to a temperature of about 40xc2x0 C. to about 80xc2x0C.
In another embodiment of the inventive method, the ozone is supplied with about 4,000 to about 30,000 ppm, preferably from the bottom of a vessel which contains the oil.
According to the invention, the ozone is supplied to the oil for about 50 to about 90 minutes.
Also according to the invention, the method may comprise a further step of adding activated kaolin to the oil received from the pre-treatment.
In a more preferred embodiment, the amount of activated kaolin added is about 5% by volume to about 8% by volume.
In an even more preferred embodiment, the kaolin is removed from the oil before further supplying ozone to the oil obtained from the pre-treatment.
The problem underlying the present invention is also solved by an oil obtainable by practicing the inventive method.
Furthermore, the problem is solved by an apparatus for refining virgin plant oil and/or vegetable oil into fuel, whereby the fuel is preferably diesel engine fuel, and the apparatus is preferably intended for use in the inventive method whereby said apparatus comprises at least
a first processing tank which is an agitation tank which comprises a propeller-like agitator which has sawtooth-edged blades.
In a preferred embodiment of the inventive apparatus the propeller-like agitator is attached to an agitation shaft below a conventional impeller.
In a further preferred embodiment of the inventive apparatus said apparatus comprises a second processing tank, wherein said tank comprises at least one of the means selected from the group comprising an agitation propeller, an ozone gas spin distributor device, an activated charcoal tube, a heater and an intake valve.
The inventors have surprisingly found that the disadvantages of the conventional methylesterification technology as stated above can be overcome by the inventive method and by the inventive apparatus. Particularly, said inventive method produces xe2x80x9ccleanxe2x80x9d exhaust gas and has a low plant construction cost and refining production cost. Besides these technical advantages, economical advantages may arise which render the method and apparatus according to the invention market-competitive.
Furthermore, the new kind of oil which can be produced according to the inventive method may be used as fuel, particularly as diesel engine fuel, and this new fuel exhibits a better quality then gasoline.
Briefly, and for purpose of illustration only and not for limitation the invention""s process is characterized by heating the virgin plant oil and/or waste vegetable oil to 40-80xc2x0 C. and agitating it by mixing it with ozone-filled water heated to 40-80xc2x0 C. while supplying ozone gas from the lower part of the tank. This agitation process separates and removes, along with the water, impurities contained in the waste vegetable oil such as glycerin and animal fatty acids.
Furthermore, inside the agitation tank, a propeller-like agitator which has sawtooth-edged blades is attached to the end of its rotational shaft. With this structure, ozone gas emitted upwards is adsorbed and decomposed by activated charcoal.
Moreover, with the aforementioned as an initial treatment, the processed oil (with its impurities separated and removed) is reheated to 40-80xc2x0 C. and refined by agitating it with fine ozone gas bubbles supplied from the lower part of the tank. This comprises the secondary treatment. Similarly, ozone gas emitted upwards in this process is adsorbed and decomposed by activated charcoal.
In summary, virgin plant oil and waste vegetable oil heated to 40-80xc2x0 C. are mixed with water, the volume of which is 3-8% by the volume of the oil and heated to 40-80xc2x0 C., and agitated by supplying ozone gas with a concentration of 4,000-30,000 ppm from the lower part of the tank. This pre-treatment process separates and removes, along with the water, impurities contained in the waste vegetable oil such as glycerin and animal fatty acids. Upon completion of the pre-treatment process, the processed oil is mixed with 5-8% activated kaolin and agitated. This primary treatment filters impurities by adsorbing them to the activated kaolin. Upon completion of the primary treatment, the processed oil is reheated to 40-80xc2x0 C. in the processing tank while being supplied from the lower part of the tank with fine ozone gas bubbles with a concentration of 4,000-30,000 ppm, and then agitated. This secondary treatment refines the processed oil.
The main difference between diesel engine fuel refined from vegetable oil and gasoline refined from petroleum is, first, the former does not contain sulfur. Due to recent environmental concerns, there has been a clamor to reduce the sulfur content of gasoline by half, and this poses a major problem for the industry. However, fuel refined from vegetable oil basically does not have this problem.
Secondly, oil used in cooking tempura and the like clogs pipes when drained down the sink, and this can prove to be a burdensome waste. The invention aims to hit two birds with one stone by effectively utilizing natural resources while solving the waste and environmental problems.
Third is the cost of production. There have been a lot of instances wherein, due to high cost, even if the process contributes to the recycle of natural resources, production is not viable. In this invention, almost no raw material is basically required aside from ozone (i.e. electrical power), activated charcoal, and activated kaolin, thus making cheap diesel engine fuel from waste vegetable oil possible.
Fourth is the quality of the diesel engine fuel. As stated below, a major part of the fuel produced through this invention has a lower molecular weight than gasoline and has a better combustibility. Moreover, its NOx emission, which along with SOx is a problem, is extremely low.
Fifth, unlike petroleum, this invention carries no tax burden and, therefore, has an added value of supplying users with cheap fuel. It is to be noted that this advantage is a more economic one and does not necessarily apply for all countries.